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Abstract:

A fabric assembly particularly useful in ballistic resistant armor has
two separate sections each containing a number of fabrics made from yarns
having a tenacity of at least 7.3 grams per dtex and a modulus of at
least 100 grams per dtex. Compressed fabrics in the first section are
employed and connected by a connector having a force to break in tension
not greater than 180 N to form delineated areas in a range from 15 square
mm to 350 square mm. Fabrics in the second section are not compressed and
are not joined other than to prevent slippage of the fabrics relative to
one another.

Claims:

1. A fabric assembly suitable for resisting a ballistic object
comprising: (a) at least one first section comprising a plurality of
connected and compacted fabric layers made from yarn having a tenacity of
at least 7.3 grams per dtex and a modulus of at least 100 grams per dtex,
wherein the connected and compacted fabric layers are secured together by
connectors having a force to break in tension not greater than 180 N,
wherein said connectors define areas within and on surfaces of the
plurality of fabric layers in a range from 15 to 350 square mm. and
wherein compaction of the fabric layers of the first section is at least
2% as set forth in Test Method A and (b) at least one second section
comprising a plurality of fabric layers made from yarn having a tenacity
of at least 7.3 grams per dtex and a modulus of at least 100 grams per
dtex wherein the fabric layers are not connected to define areas in a
range from 15 to 350 square mm. and wherein compaction of the fabric
layers of the second section is not greater than 0.5% as set forth in
Test Method A.

2. The fabric assembly of claim 1 wherein the fabrics of the second
section are connected only with sufficient mechanical strength to prevent
slippage of the layers relative to one another.

3. The fabric assembly of claim 1 wherein the total number of fabric
layers of the first and second sections, when stacked together, have an
areal density less than 5.0 kg/m.sup.2.

4. A connector of claim 1 in the form of a thread comprising filaments of
cotton, polyester, p-aramid, elastomeric polyurethane and mixtures
thereof.

5. The fabric of claim 1, wherein the continuous yarns are made of
filaments made from a polymer selected from the group consisting of
polyamides, polyolefins, polyazoles, and mixtures thereof.

6. A process for making a fabric assembly for an armor article comprising
the steps of: (a) stacking a plurality of layers of fabric made from
continuous yarn having a tenacity of at least 7.3 grams per dtex and a
modulus of at least 100 grams per dtex, (b) compacting and securing said
plurality of fabric layers to form a first section by inserting
connectors through the fabric layers, said connectors forming a pattern
of lines on the surface of the fabric, said connectors further having a
mechanical strength such that the force to break in tension of each
connector is no greater than 180 N wherein said connector lines further
define the perimeter of areas of compacted fabric enclosed by the
connectors, said enclosed compacted areas being greater than 15 sq. mm.
and less than 350 sq. mm. on the compacted fabric layer surfaces, so as
to provide a compacted bundle having a compaction of at least 2.0% as set
forth in Test Method A (c) stacking a plurality of layers of fabric made
from continuous yarn having a tenacity of at least 7.3 grams per dtex and
a modulus of at least 100 grams per dtex, (d) forming a second section by
securing said plurality of fabric layers at the corners and around the
edges so as to provide a cohesive bundle having a compaction not greater
than 0.5% as set forth in Test Method A, and (e) combining at least one
first section with at least one second section into a fabric assembly.

7. The fabric assembly of claim 6 wherein the total number of fabric
layers of the first and second sections, when stacked together, have an
areal density less than 5.0 kg/m.sup.2.

Description:

RELATED APPLICATION

[0001] The present patent application is a continuation-in-part of Ser.
No. 12/369,227 filed Feb. 11, 2009 which in turn is a
continuation-in-part of Ser. No. 12/368,539 filed Feb. 10, 2009.

BACKGROUND OF INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to a fabric assembly particularly suitable
for use in ballistic resistant armor and a method of manufacture.

[0004] 2. Description of the Related Art

[0005] Many designs for body armor for resisting ballistic threats have
been proposed and many commercialized. Designs are made to increase
comfort by the wearer and/or to add extra penetration resistance without
increasing areal density. Comfort is generally increased by making the
body armor lighter and more flexible to allow freedom of motion by the
wearer. However, reduction in apparel weight should not be achieved at
the expense of a significant reduction in anti-ballistic performance.

[0006] US 2008/0075933 A1 discloses a ballistic-resistant assembly
containing flexible elements of high strength fibers having connecting
means on a rear part side of the assembly to interconnect adjacent
elements. Such assemblies are claimed to reduce trauma (back face
deformation) during a ballistic event.

[0007] Niemi and Cuniff in Technical Note Natick/TN-91/0004 with a title
"The Performance of Quilted Body Armor Systems Under Ballistic Impact by
Right Circular Cylinders" state that "Based on results obtained with 1.1
gram right circular cylinders, the effect of quilting resulted in little
or no increase in the calculated ballistic limit values or specific
energy absorption capacity of the Kevlar®, Spectra® and nylon
armor systems evaluated".

[0008] There is a need for a light weight soft body armor which allows an
increase in ballistic resistance without an increase in weight.

SUMMARY OF THE INVENTION

[0009] The present invention is directed to a fabric assembly suitable for
use in ballistic resistant armor and a method of manufacture with the
fabric assembly comprising:

[0010] (a) a first section comprising a plurality of connected and
compacted fabric layers made from yarn having a tenacity of at least 7.3
grams per dtex and a modulus of at least 100 grams per dtex,

[0011] wherein the connected and compacted fabric layers are secured
together by connectors having a force to break in tension not greater
than 180 N,

[0012] wherein said connectors define areas within and on surfaces of the
plurality of fabric layers in a range from 15 to 350 square mm. and

[0013] wherein compaction of the fabric layers of the first section is at
least 2% as set forth in Test Method A and

[0014] (b) a second section comprising a plurality of fabric layers made
from yarn having a tenacity of at least 7.3 grams per dtex and a modulus
of at least 100 grams per dtex

[0015] wherein the fabric layers are not connected to define areas in a
range from 15 to 350 square mm. and

[0016] wherein compaction of the fabric layers of the second section is
not greater than 0.5% as set forth in Test Method A.

BRIEF DESCRIPTION OF DRAWINGS

[0017] FIG. 1A is a plan view of the outer fabric layers (plies) of the
first section and explains connector lines, connector length, connector
row spacing and connector area.

[0018] FIG. 1B is an end view of a staple or clip connector.

[0019] FIG. 1C is a plan view showing a pin pattern of connectors through
fabric plies.

[0020] FIG. 2 is a plan view of fabric layers of the second section
without connectors and held together by corner tack stitching.

[0021] FIG. 3A is a sectional view of a plurality of fabric layers of the
first section having connectors. This is referenced as "A".

[0022] FIG. 3B is a sectional view of a plurality of fabric layers of the
second section having no connectors. This is referenced as "B".

[0023] FIG. 4 is a sectional view of a vest stack having a first section
per A of FIG. 3A as a strike face and a second section per B of FIG. 3B
as a back face.

[0024] FIG. 4A is a sectional view of a vest stack assembled from a number
of sub-assemblies of fabric layers A at the strike face and a number of
sub-assemblies of fabric layers B at the back face.

[0025] FIG. 5 is a sectional view of a vest stack having a repeat sequence
of A and B.

[0026] FIG. 6A is a sectional view of a vest stack having first sections
per A of FIG. 3A as a strike face and a back face sandwiching a core
having a second section per B of FIG. 3B.

[0027] FIG. 6B is a sectional view of a vest stack having second sections
per B of FIG. 3B as a strike face and back face sandwiching a core having
a first section per A of FIG. 3A.

DETAILED DESCRIPTION

[0028] The fabric assembly suitable for resisting a ballistic object
contains two separate and distinct sections labeled herein as a first
section and a second section. Both sections contain a plurality of fabric
layers made from yarns having a tenacity of at least 7.3 grams per dtex
and a modulus of at least 100 grams per dtex.

[0029] As employed herein "plurality" means at least two. However in many
instances at least five and sometimes at least ten or up to thirty fabric
layers will be employed in the first and/or second sections of the fabric
assembly.

Yarns in First and Second Sections of Fabric Assembly

[0030] Yarns having a tenacity of at least 7.3 grams per dtex and a
modulus of at least 100 grams per dtex which are employed in the first
and second sections are well known in the art. It is understood that the
yarns in the first and second sections need not be identical. Suitable
materials for the yarn include polyamide, polyolefin, polyazole and
mixtures thereof.

[0032] A preferred aramid is a para-aramid. A preferred para-aramid is
poly(p-phenylene terephthalamide) which is called PPD-T. By PPD-T is
meant a homopolymer resulting from mole-for-mole polymerization of
p-phenylene diamine and terephthaloyl chloride and, also, copolymers
resulting from incorporation of small amounts of other diamines with the
p-phenylene diamine and of small amounts of other diacid chlorides with
the terephthaloyl chloride. As a general rule, other diamines and other
diacid chlorides can be used in amounts up to as much as about 10 mole
percent of the p-phenylene diamine or the terephthaloyl chloride, or
perhaps slightly higher, provided only that the other diamines and diacid
chlorides have no reactive groups which interfere with the polymerization
reaction. PPD-T, also, means copolymers resulting from incorporation of
other aromatic diamines and other aromatic diacid chlorides such as, for
example, 2,6-naphthaloyl chloride or chloro- or dichloroterephthaloyl
chloride or 3,4'-diaminodiphenylether.

[0033] Additives can be used with the aramid and it has been found that up
to as much as 10 percent or more, by weight, of other polymeric material
can be blended with the aramid. Copolymers can be used having as much as
10 percent or more of other diamine substituted for the diamine of the
aramid or as much as 10 percent or more of other diacid chloride
substituted for the diacid chloride or the aramid.

[0034] When the polymer is polyolefin, polyethylene or polypropylene is
preferred. The term "polyethylene" means a predominantly linear
polyethylene material of preferably more than one million molecular
weight that may contain minor amounts of chain branching or comonomers
not exceeding 5 modifying units per 100 main chain carbon atoms, and that
may also contain admixed therewith not more than about 50 weight percent
of one or more polymeric additives such as alkene-1-polymers, in
particular low density polyethylene, propylene, and the like, or low
molecular weight additives such as anti-oxidants, lubricants,
ultra-violet screening agents, colorants and the like which are commonly
incorporated. Such is commonly known as extended chain polyethylene
(ECPE) or ultra high molecular weight polyethylene (UHMWPE

[0035] In some preferred embodiments polyazoles are polyarenazoles such as
polybenzazoles and polypyridazoles. Suitable polyazoles include
homopolymers and, also, copolymers. Additives can be used with the
polyazoles and up to as much as 10 percent, by weight, of other polymeric
material can be blended with the polyazoles. Also copolymers can be used
having as much as 10 percent or more of other monomer substituted for a
monomer of the polyazoles. Suitable polyazole homopolymers and copolymers
can be made by known procedures.

[0036] Preferred polybenzazoles are polybenzimidazoles,
polybenzothiazoles, and polybenzoxazoles and more preferably such
polymers that can form fibers having yarn tenacities of 30 gpd or
greater. If the polybenzazole is a polybenzothioazole, preferably it is
poly(p-phenylene benzobisthiazole). If the polybenzazole is a
polybenzoxazole, preferably it is poly(p-phenylene benzobisoxazole) and
more preferably poly(p-phenylene-2,6-benzobisoxazole) called PBO.

[0037] Preferred polypyridazoles are polypyridimidazoles,
polypyridothiazoles, and polypyridoxazoles and more preferably such
polymers that can form fibers having yarn tenacities of 30 gpd or
greater. In some embodiments, the preferred polypyridazole is a
polypyridobisazole. A preferred poly(pyridobisozazole) is
poly(1,4-(2,5-dihydroxy)phenylene-2,6-pyrido[2,3-d:5,6-d']bisimidazole
which is called PIPD. Suitable polypyridazoles, including
polypyridobisazoles, can be made by known procedures.

First Section of Fabric Assembly

[0038] The requirements of the yarn in the fabrics of the first section of
the fabric assembly have been set forth above.

[0039] Further requirements of the first section include fabrics which (1)
are connected to one another (2) are compacted, (3) are secured together
by connectors having a force to break in tension not greater than 180
Newtons (N), (4) have areas in a range from 15 square mm to 350 square mm
defined by the connectors and (5) have compaction of at least 2% as set
forth in Test Method A.

[0040] Requirements (1), (3) and (4) are discussed in conjunction with one
another.

[0041] It is necessary that the fabrics of the first section be physically
attached to one another. The attachment of the fabric layers is by
connectors having a force to break in tension of not greater than 180 N.
In some embodiments, the mechanical strength will not be greater than 150
N or even 90 N. In other embodiments, the force to break will not be
greater than 65 N or even 40 N. In yet other embodiments, the force to
break will not be greater than 35 N. The lower limit for a force to break
is not critical but as a practical matter will not be less than 1 N. For
soft body armor it is preferable that the force to break in tension of
the connector is not greater than 65 N but for hard armor it is
preferable that the force to break of the connector is not greater than
180 N.

[0042] The force to break in tension of the connector is the multiplier of
the ultimate tensile stress of the connector material, or materials, and
the cross sectional area of the connector. Thus the dimensions of the
connector can be tailored to achieve the desired force to break for a
particular material. For chemical connectors the desired dimension is the
area of adhesion between two adjacent fabric layers.

[0043] A preferred connector is through the use of thread for stitching,
i.e. the separate fabric layers of the first section are stitched
together. The thread may be a continuous filament yarn or a staple fiber.
In machine stitching, it is common to loop two threads together one
thread being fed from the top side and the other being fed from the
bottom side. When such a stitching technique is being used to sew
connector threads then at least one of the bobbins must be of a material
having a force to break no greater than 180 N. If a plied yarn is used as
a connector thread, then the combined force to break of the individual
threads comprising the yarn must be no greater than 180 N. A plied yarn
is a yarn formed by twisting together two or more singles yarns. Suitable
thread materials include aramid, cotton, nylon, polyester or elastomeric
polyurethane (Lycra®). A connector yarn that shrinks when heated is
an alternative means to compact fabric layers.

[0044] However it is understood that connectors other than stitching
thread or yarn may be employed The connectors can be mechanical such as
by stapling or by chemical means. It is understood that the connectors
need not contact one another provide the area delineated by the
connectors.

[0045] Mechanical connectors can be in many forms not only by thread but
also by clips, pins, needles or staples and made of polymeric, metal,
ceramic or other inorganic material. For pins, clips, needles or staples
suitable materials include carbon, glass, ceramic, metal or polymer.

[0046] An example of a chemical connector is an adhesive. It is preferable
that the adhesive has a modulus no greater than 1379 MPa. The adhesive
may be thermoset or thermoplastic preferably curing between 20° C.
to 180° C. and more preferably between 20° C. to
120° C. The adhesive may be in the form of a liquid, paste, powder
or film. Suitable materials include epoxy, phenolic, urethane, polyester,
vinyl ester, polyimide or maleimide. The adhesive connectors may take the
form of continuous or broken lines, dots, ovals, diamonds and other
shapes.

[0047] As set forth above, a connector is required to have a force to
break in tension not greater than 65 N for soft armor or 180 N for hard
armor. In the case of a mechanical connector the force to break can be
determined by testing the connector prior to use. However for a chemical
connector, typically it is necessary to determine the mechanical strength
in actual use with layers of fabric.

[0048] Connector pitch length is (1) for stitches, the minimum distance
that the needle advances along a connector line on the surface of the
fabric in making one stitch, (2) for clips and staples, the length of the
clip or staple and (3) for pins, the minimum distance between two
adjacent connectors on the same connector line. This is further detailed
in FIGS. 1A to 1C.

[0049] Connector area is the area enclosed by a boundary of connector
lines.

[0051] The function of the connector is to enhance the momentum transfer
capability of the armor without impacting the mechanical properties of
the high tenacity filaments in the fabric. Another requirement is not to
over-constrain the axial movement of the filaments in the fabric.

[0052] To enhance the momentum transfer, the connectors need to be able to
compact the fabric layers in the region where the connector lies on the
fabric surface. The connectors also define areas on a surface and within
each of the connected fabrics of the first section of the fabric assembly
The surface areas are in a range from 15 to 350 square mm, a preferred
range is 100 to 250 square mm and a more preferred range is 115 to 180
square mm. The number of defined areas in the first section of the fabric
assembly will be determined by the overall size of the fabric assembly

[0053] The connector may be of any suitable length. Preferably the length
is from 2.54 to 15.24 mm and more preferably from 3.56 to 14.22 mm. For
adhesive dots, ovals and the like, the length is the maximum dimension of
the adhesive dot or oval. The area enclosed by the connectors is more
important than the area shape. Suitable area shapes defined by connector
lines include, but are not limited to, squares, rectangles, triangles,
hexagons, diamonds and chevrons. For practical reasons, connector areas
below 15 sq. mm. are less desirable due to the risk of yarn damage from
the connector insertion process.

[0054] Techniques for inserting connectors are well known and include
sewing, for thread, and pressure guns, ultrasonics and the like for pins,
needles and staples. All these techniques are well known in the textile
art.

[0055] When connectors are of the sewn type, the type of stitches employed
is not critical and may vary widely provided that the required
relationships for pitch length and row spacing are followed. Stitching
and sewing methods such as hand stitching, multi-thread chain stitching,
over edge stitching, flat seam stitching, single thread lock stitching,
lock stitching, chain stitching, zig-zag stitching and the like
constitute the preferred securing means for use in this invention.

[0056] In order to minimize damage to the yarns of the fabric layers, and
hence ballistic resistance, it is preferable that the connector lines are
positioned in a direction such that they form an angle of between five
and eighty five degrees with both the warp and weft yarns of the fabric.
More preferably this angle should be between twenty and seventy degrees.

[0057] A further requirement of the first section of the fabric assembly
is use of fabrics which are compacted and have compaction of at least 2%
as set forth in Test Method A. This test defines a procedure wherein the
thickness of a fabric is first measured after manufacture and without
further handling to decrease the fabric thickness. The thickness of a
fabric is then measured after compaction for use in the first section of
the fabric assembly. The compaction expressed on a % basis is the amount
of decrease of fabric thickness based on the original fabric thickness.

[0058] The compacted fabrics for the first section of the fabric assembly
will have a compaction of at least 2%, preferably at least 5% and more
preferably at least 7%. For purposes of illustration the compaction will
not be greater than 20% with a narrower maximum of 15%.

Second Section of Fabric Assembly

[0059] The requirements of the yarn in the fabrics of the second section
of the fabric assembly have been set forth above. The fibers of the
second section may be different from those of the first section.

[0060] Further requirements of the second section include (1) the fabrics
are not connected to define areas in a range from 15 to 350 square mm and
(2) compaction of the fabrics is not greater than 0.5% as set forth in
test method A. These essentially non-compacted fabrics are also known in
the art as loose plies.

[0061] For requirement (1) of the second section of the fabric assembly,
it is preferred that the fabric layers are not connected to one another.
However it is understood that in manufacture of the overall fabric
assembly it may be advisable to keep the layers aligned without slipping.
Therefore, as employed herein, "substantially no connection" means that
the amount of connection is an amount needed to prevent slipping but
insufficient to force the layers to compact one another. An example of
this is corner stitching as depicted in FIG. 2. Accordingly the second
section preferably has substantially no connection between and among (if
more than two) fabrics. For requirement (2) of the second section of the
fabric assembly, it is preferred the there is no compaction of the
fabrics. However in normal handling and in manufacture a minimum
compaction can occur. Therefore a maximum compaction as set forth in Test
Method A is not greater than 0.5%, preferably 0.2% and more preferably
0%.

Construction of Fabrics

[0062] It is understood that a wide variety of construction techniques may
be used for the fabrics of the first and second sections of the fabric
assembly. Illustratively the fabrics may be woven, may be unidirectional
with or without binder, may be multiaxial with layers of yarn in
different orientation or may be three dimensional. Each of these fabric
styles is well known in the art. It is further understood that different
combinations of fabrics both in construction and composition can be
employed in the first section and in the second section of the fabric
assembly.

Ballistic Resistant Armor Article

[0063] An example of a soft body armor article is a vest. An example of a
hard body armor article is a helmet or tactical plate. An example of
another type of hard armor article is a plate for a vehicle such as a
25.4 mm thick plate.

[0064] The armor article comprises at least two fabric layer
sub-assemblies, one sub-assembly comprising fabric layers having
connectors, the first section, and the other comprising fabric layers
without connectors, the second section. Each sub-assembly can have from
two to thirty woven fabric layers stacked together. The woven fabric
layers in the different sub-assemblies can be the same or different. A
final assembly comprises at least one type of each sub-assembly. The
final assembly is then fitted into a vest pack or body armor article.

[0065] For soft body armor, the total number of fabric layers from all of
the sub-assemblies comprising the final assembly, when stacked together,
should preferably have an areal density no greater than 5.0 kg/m2
and preferably no greater than 4.68 kg/m2. For hard body armor such
as a helmet, the total number of fabric layers from all of the
sub-assemblies comprising the final assembly, when stacked together,
should preferably have an areal density no greater than 12.5 kg/m2.
For a thick armor plate of 25.4 mm thickness, the total number of fabric
layers from all of the sub-assemblies comprising the final assembly, when
stacked together, should preferably have an areal density no greater than
19 kg/m2.

[0066] Depending on the ballistic resistant article design, the number of
fabric layers requiring connectors will vary. The location of layers
having connectors and those not having connectors can vary within the
assembly e.g. see FIGS. 4, 4A, 5, 6A and 6B. In these figures, a fabric
layer identified with an "A" has connectors and those identified by a "B"
has no connectors. Combinations of sub-assemblies other than those
described in the drawings are also useful.

[0067] In a first embodiment as shown in FIG. 4, a sub-assembly "A"
comprising fabric layers having connectors is facing the strike direction
while a sub-assembly "B" comprising fabric layers without connectors is
facing the non-strike direction.

[0068] In a second embodiment, a number of sub-assemblies each comprising
fabric layers having connectors is facing the strike direction while a
number of sub-assemblies each comprising layers without connectors is
facing the non-strike direction. This is exemplified by FIG. 4A which
shows three sub-assemblies of fabric layers with connectors, A1, A2 and
A3, facing the projectile and three sub-assemblies of fabric layers
without connectors, B1, B2 and B3, facing the non-strike direction.

[0069] A third embodiment, as in FIG. 5, covers an arrangement of
alternating sub-assemblies of fabric layers having connectors "A" and
fabric layers without connectors "B".

[0070] In a fourth embodiment, two sub-assemblies each comprising fabric
layers having connectors form the two outer layers of the final assembly
with a sub-assembly comprising fabric layers without connectors forming
the core of the assembly. This is demonstrated in FIG. 6A.

[0071] In a fifth embodiment, two sub-assemblies each comprising fabric
layers without connectors form the two outer layers of the final assembly
with a sub-assembly comprising fabric layers having connectors forming
the core of the assembly. This is demonstrated in FIG. 6B.

[0072] The fabric layers of the sections without connectors must be held
together to maintain a certain level of coherence. These layers can, for
example, be attached by stitches or adhesive or melt bonding at the edges
and/or across the corners of the fabric. These stitches in the fabric
layers do not compact the layers in the same way as do the connectors and
have no influence on anti-ballistic performance. Any suitable thread may
be used for sewing at the edges and corners. Aramid thread is
particularly suitable for edge and corner stitching. Edge or corner
stitching is an optional process for the fabric layers having connectors,
the benefit being that it may aid the final assembly process.

[0073] For hard armor, the fabrics of the first and second sections may be
impregnated with a resin. The resin may be thermoplastic, thermoset or a
mixture of both. A widely used and commercially available resin is
PVB-phenolic. The resin content is normally from 5 to 30 weight percent
of the weight of fabric plus resin.

[0074] Preferably, for soft body armor, the ballistic resistant fabric
final assembly has a V50 of at least 465 m/sec when tested against a 9 mm
projectile and/or V50 of at least 579 m/sec when tested against a 17
grain projectile and the fabric layers, when stacked together, have a
stack areal density not exceeding 4.68 kg/m2. V50 is a statistical
measure that identifies the average velocity at which a bullet or a
fragment penetrates the armor equipment in 50% of the shots, versus non
penetration of the other 50%. The parameter measured is V50 at zero
degrees where the degree angle refers to the obliquity of the projectile
to the target.

[0075] For hard armor, incorporating connectors as described herein in a
ballistic resistant fabric final assembly will lead to increased V50
performance from the fibrous component of the hard armor article.

Method of Assembly

[0076] A process for making a fabric assembly for an armor article
comprises the steps of (1) forming an assembly or sub-assemblies of
fabric layers comprising connectors having a force to break of no greater
than 65 N for soft armor or 180 N for hard armor such that the area
enclosed by the connectors is from 30 to 350 sq. mm (2) forming an
assembly or sub-assemblies of fabric layers having no connectors and
stitching these layers along the edges and/or across the corners (3)
combining the assemblies or sub-assemblies in the desired sequence such
that the total weight of all fabric layers is less than 5.0 kg/m2
and more preferably less than 4.68 kg/m2 for soft armor or less than
12.5 kg/m2 for hard body armor and, for soft armor, placing the
final fabric assembly in a pouch or vest pack. For hard armor the
assembly is then subjected to consolidation under heat and pressure. In
an alternative embodiment, the connectors may be applied to a hard armor
assembly after consolidation.

[0078] Linear Density The linear density of a yarn or fiber is determined
by weighing a known length of the yarn or fiber based on the procedures
described in ASTM D1907-97 and D885-98. Decitex or "dtex" is defined as
the weight, in grams, of 10,000 meters of the yarn or fiber. Denier (d)
is 9/10 times the decitex (dtex).

[0079] Tensile Properties: The fibers to be tested were conditioned and
then tensile tested based on the procedures described in ASTM D885-98.
Tenacity (breaking tenacity), modulus of elasticity, force to break and
elongation to break are determined by breaking test fibers on an Instron
universal test machine.

[0080] Areal Density: The areal density of the fabric layer was determined
by measuring the weight of each single layer of selected size, e.g., 10
cm×10 cm. The areal density of a composite structure was determined
by the sum of the areal densities of the individual layers.

[0081] Ballistic Penetration Performance: Ballistic tests of the
multi-layer panels were conducted in accordance with standard procedures
such as those described in procurement document FQ/PD 07-05B (Body Armor,
Multiple Threat/Interceptor Improved Outer Tactical Vest) and MIL
STD-662F (V50 Ballistic Test for Armor). Four targets were tested for
most examples and between six to nine shots, at zero degree obliquity,
fired at each dry target. The reported V50 values are average values for
the number of shots fired for each example.

EXAMPLES

[0082] Examples prepared according to the process or processes of the
current invention are indicated by numerical values. Control or
Comparative Examples are indicated by letters. Data and test results
relating to the Comparative and Inventive Examples are shown in Table 1.

Description of Layers

[0083] Layers of the following high tenacity fiber fabrics and sheet
structures were prepared and made into various composite assemblies for
ballistic test as follows.

[0084] (S15351F) Fabric layer "F1" was a plain weave woven fabric of 600
denier (660 dtex) poly(p-pheynlene terephthalamide) (or PA) yarn
available from E. I. du Pont de Nemours and Company under the trade name
of Kevlar® para-aramid brand KM2 yarn and was woven at
11.1×11.1 ends per centimeter (28×28 ends per inch).

[0085] (S706F) Fabric layer "F2" was a plain weave woven fabric of 600
denier (660 dtex) poly(p-pheynlene terephthalamide) (or PA) yarn
available from E. I. du Pont de Nemours and Company under the trade name
of Kevlar® para-aramid brand KM2 yarn and was woven at
13.5×13.5 ends per centimeter (34×34 ends per inch).

[0086] (S751F) Fabric layer "F3" was a plain weave woven fabric of 600
denier (660 dtex) poly(p-pheynlene terephthalamide) (or PA) yarn
available from E. I. du Pont de Nemours and Company under the trade name
of Kevlar® para-aramid brand KM2 yarn and was woven at
11.4×11.4 ends per centimeter (29×29 ends per inch).

[0087] A thermoplastic film interleave "IL1" was used with the hard armor
fabric assemblies. The film was a blend of elastomeric block copolymers
and polyethylene copolymers with the polyethylene copolymers comprising
from 50 to 75 weight percent and the elastomeric block copolymers
comprising from 25 to 50 weight percent of the resin. The films were
0.0125 mm thick and were perforated.

[0088] For examples pertaining to soft armor, the above fabric layers were
assembled and then, prior to shooting, were placed in a nylon bag of
about 38 cm×38 cm (15''×15''). The side of the bag facing the
projectile was 900 dtex (1000 denier) Woodland Camouflage Cordura rip
stop fabric and the other side was 450 dtex (500 denier) Black Cordura
rip-stop fabric. Both fabrics were obtained from Bradford Printing &
Finishing LLC, Bradford, R.I.

[0089] The connector threads were all sewn using a Juki sewing machine,
model LU 563.

[0090] Examples A to L and 1 to 12 pertain to structures suitable for soft
body armor. Examples M, N, 13 and 14 pertain to structures suitable for
hard armor

Example A

[0091] Twenty eight layers of fabric F2 of about 38 cm×38 cm
(15''×15'') were held together by stitches located at the four
corners of the layers (corner stitch) into an article with an areal
density of 5.23 kg/m2. The corner stitching thread was 800 dtex (720
denier) Kevlar® under the tradename B-92 from Imperial Threads Inc.,
Northbrook, Ill. Ballistic tests were conducted using 9 mm 124 grain FMJ
bullets against targets supported on a Roma Plastina number 1 clay
backing medium. Results of the ballistic tests of four targets gave V50
values between 478 and 500 m/s with an average value of 488 m/s.

Example B

[0092] In this example, twenty six layers of fabric F2 of about 38
cm×38 cm (15''×15'') were held together by stitches located
at the four corners of the layers (corner stitch) into an article with an
areal density of 4.88 kg/m2. The corner stitching thread was 800
dtex (720 denier) Kevlar® under the tradename B-92 from Imperial
Threads Inc. Ballistic tests were conducted using 9 mm 124 grain FMJ
bullets against targets supported on a Roma Plastina number 1 clay
backing medium. Results of the ballistic tests of four targets gave V50
values between 474 and 497 m/s with an average value of 483 m/s.

Example C

[0093] Thirty five layers of fabric layers F1 of about 38 cm×38 cm
(15''×15'') were held together by stitches located at the four
corners of the layers (corner stitch) into an article with an areal
density of 5.28 kg/m2. The corner stitching thread was 800 dtex (720
denier) Kevlar® under the tradename B-92 from Imperial Threads Inc.
Ballistic tests were conducted using 9 mm 124 grain FMJ bullets against
targets supported on a Roma Plastina number 1 clay backing medium.
Results of the ballistic tests of four targets gave V50 values between
496 and 525 m/s with an average value of 511 m/s.

Example D

[0094] Thirty one layers of fabric layers F1 of about 38 cm×38 cm
(15''×15'') were held together by stitches located at the four
corners of the layers (corner stitch) into an article with an areal
density of 4.68 kg/m2. The corner stitching thread was 800 dtex (720
denier) Kevlar® under the tradename B-92 from Imperial Threads Inc.
Ballistic tests were conducted using 9 mm 124 grain FMJ bullets against
targets supported on a Roma Plastina number 1 clay backing medium.
Results of the ballistic tests of four targets gave V50 values between
454 and 466 m/s with an average value of 462 m/s.

Example E

[0095] Twenty eight layers of fabric F2 of about 38 cm×38 cm
(15''×15'') were held together by stitches located at the four
corners of the layers (corner stitch) into an article with an areal
density of 5.23 kg/m2. The corner stitching thread was 800 dtex (720
denier) Kevlar® under the tradename B-92 from Imperial Threads Inc.
Ballistic tests were conducted using 17 grain fragment simulating
projectiles (FSP's) against targets supported on an aluminum 24 ga, 0.20,
2024-T3 frame and clamp backing plate. Results of the ballistic tests of
four targets gave V50 values between 563 and 612 m/s with an average
value of 577 m/s.

Example F

[0096] Twenty six layers of fabric F2 of about 38 cm×38 cm
(15''×15'') were held together by stitches located at the four
corners of the layers (corner stitch) into an article with an areal
density of 4.88 kg/m2. The corner stitching thread was 800 dtex (720
denier) Kevlar® under the tradename B-92 from Imperial Threads Inc.
Ballistic tests were conducted using 17 grain FSP's against targets
supported on an aluminum 24 ga, 0.20, 2024-T3 frame and clamp backing
plate. Results of the ballistic tests of four targets gave V50 values
between 532 and 582 m/s with an average value of 558 m/s.

Example G

[0097] Thirty five layers of fabric layers F1 of about 38 cm×38 cm
(15''×15'') were held together by stitches located at the four
corners of the layers (corner stitch) into an article with an areal
density of 5.28 kg/m2. The corner stitching thread was 800 dtex (720
denier) Kevlar® under the tradename B-92 from Imperial Threads Inc.
Ballistic tests were conducted using 17 grain FSP's against targets
supported on an aluminum 24 ga, 0.20, 2024-T3 frame and clamp backing
plate. Results of the ballistic tests of four targets gave V50 values
between 573 and 606 m/s with an average value of 592 m/s.

Example H

[0098] Thirty one layers of fabric layers F1 of about 38 cm×38 cm
(15''×15'') were held together by stitches located at the four
corners of the layers (corner stitch) into an article with an areal
density of 4.68 kg/m2. The corner stitching thread was 800 dtex (720
denier) Kevlar® under the tradename B-92 from Imperial Threads Inc.
Ballistic tests were conducted using 17 grain FSP's against targets
supported on an aluminum 24 ga, 0.20, 2024-T3 frame and clamp backing
plate. Results of the ballistic tests of six targets gave V50 values
between 553 and 578 m/s with an average value of 565 m/s.

Example J

[0099] In this example, thirteen layers of fabric F2 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through and orthogonal to the thirteen layers. The connector material was
961 dtex (865 denier) Kevlar® spunthread from Saunders Thread
Company, Gaston, N.C. having a force to break of 69.8 N. The connector
pitch length was 6.4 mm and the connector row spacing was 12.8 mm. The
connector lines enclosed a connector area of 161 sq. mm. The sub-assembly
with the connectors was then combined with 13 loose layers, 38
cm×38 cm (15''×15''), of fabric F2 by corner stitching into
an article with an areal density of 4.88 kg/m2. The corner stitching
thread was 800 dtex (720 denier) Kevlar® under the tradename B-92
from Imperial Threads Inc. Ballistic tests were conducted using 17 grain
fragment simulating projectiles (FSP's) against targets supported on an
aluminum 24 ga, 0.20, 2024-T3 frame and clamp backing plate. The test
articles were arranged in the tests such that the layers having the
connectors were facing the projectile. Results of the ballistic tests of
four targets gave V50 values between 521 and 562 m/s with an average
value of 547 m/s.

Example K

[0100] In this example, fifteen layers of fabric F1 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through and orthogonal to the fifteen layers. The connector material was
961 dtex (865 denier) Kevlar® spunthread from Saunders Thread Company
having a force to break of 69.8 N. The connector pitch length was 6.4 mm
and the connector row spacing was 12.8 mm. The connector lines enclosed a
connector area of 161 sq. mm. The sub-assembly with the connectors was
then combined with sixteen loose layers of fabric F1 of about 38
cm×38 cm (15''×15'') by corner stitching into an article with
an areal density of 4.68 kg/m2. The corner stitching thread was 800
dtex (720 denier) Kevlar® under the tradename B-92 from Imperial
Threads Inc. Ballistic tests were conducted using 17 grain fragment
simulating projectiles (FSP's) against targets supported on an aluminum
24 ga, 0.20, 2024-T3 frame and clamp backing plate. The test articles
were arranged in the tests such that the layers having the connectors
were facing the projectile. Results of the ballistic tests of four
targets gave V50 values between 554 and 586 m/s with an average value of
571 m/s.

Example L

[0101] In this example, twenty six layers of fabric F2 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through and orthogonal to all the layers. The connector material was 453
dtex (408 denier) cotton thread from United Mills having a force to break
of 18.5 N. The connector pitch length was 6.4 mm and the connector row
spacing was 12.8 mm. The connector lines enclosed a connector area of 161
sq. mm. In addition, stitches were located at the four corners of the
layers (corner stitch) giving an article with an areal density of 4.68
kg/m2. The corner stitching thread was 800 dtex (720 denier)
Kevlar® under the tradename B-92 from Imperial Threads Inc. Ballistic
tests were conducted using 17 grain FSP's against targets supported on an
aluminum 24 ga, 0.20, 2024-T3 frame and clamp backing plate. Results of
the ballistic tests of four targets gave V50 values between 499 and 532
m/s with an average value of 518 m/s.

Example M

[0102] In this example, sixty layers of fabric F3 of about 38 cm×38
cm (15''×15'') were assembled with a perforated film layer IL1
between each fabric layer. The assembly of film and fabric had an areal
density before consolidation of 9.89 kg/m2. The assembly was
consolidated to form a hard plate at a pressure of 0.42 bar, a
temperature of 178° C. with a hot press time of 15 minutes
followed by a dwell time of 30 minutes. The resin content of the
fabric-film assembly after consolidation was about 6.2 percent. The areal
density of the plate after consolidation was 9.82 kg/m2 Ballistic
tests were conducted using 16 grain RCC steel projectiles. Results of the
ballistic tests gave a V50 value of 869 m/s.

Example N

[0103] Example N was as Example M except that the areal density of the
fabric-film assembly before consolidation of 9.88 kg/m2. The areal
density of the fabric-film assembly after consolidation of 9.81
kg/m2. Ballistic tests were conducted using 16 grain RCC
projectiles. Results of the ballistic tests gave a V50 value of 883 m/s.

Example 1

[0104] In this example, thirteen layers of fabric F2 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through, and orthogonal to, the thirteen layers. The connector material
was 453 dtex (408 denier) cotton thread from United Thread Mills having a
force to break of 18.5 N. The connector pitch length was 6.4 mm and the
connector row spacing was 12.8 mm. The connector lines enclosed a
connector area of 161 sq. mm. The sub-assembly with the connectors was
then combined with 13 loose layers, 38 cm×38 cm (15''×15''),
of fabric F2 by corner stitching into an article with an areal density of
4.88 kg/m2. The corner stitching thread was 800 dtex (720 denier)
Kevlar® under the tradename B-92 from Imperial Threads Inc. Ballistic
tests were conducted using 9 mm 124 grain FMJ bullets against targets
supported on a Roma Plastina number 1 clay backing medium. The test
articles were arranged in the tests such that the layers having the
connectors were facing the projectile. Results of the ballistic tests of
four targets gave V50 values between 484 and 493 m/s with an average
value of 487 m/s.

[0105] Example B had had one firing where an abnormally high V50 value was
observed thus giving a higher average value. However Example 1, having
fabric layers with connectors in an assembly having a seven percent lower
areal density than the control Example A did not exhibit any reduction in
V50 when compared to Example A.

Example 2

[0106] In this example, fifteen layers of fabric F1 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through, and orthogonal to, the fifteen layers. The connector material
was 453 dtex (408 denier) cotton thread from United Thread Mills having a
force to break of 18.5 N. The connector pitch length was 6.4 mm and the
connector row spacing was 12.8 mm. The connector lines enclosed a
connector area of 161 sq. mm. The sub-assembly with the connectors was
then combined with sixteen loose layers of fabric F1 of about 38
cm×38 cm (15''×15'') by corner stitching into an article with
an areal density of 4.68 kg/m2. The corner stitching thread was 800
dtex (720 denier) Kevlar® under the tradename B-92 from Imperial
Threads Inc. Ballistic tests were conducted using 9 mm 124 grain FMJ
bullets against targets supported on a Roma Plastina number 1 clay
backing medium. The test articles were arranged in the tests such that
the layers having the connectors were facing the projectile. Results of
the ballistic tests of four targets gave V50 values between 483 and 498
m/s with an average value of 492 m/s.

[0107] Comparison of results for examples C, D and 2 show that Example C
having an article weight of 5.28 kg/m2 had an acceptable V50 whereas
Example D at a reduced areal density of 4.68 kg/m2 had a V50 value
ten percent lower and just below the desired target value. Example 2,
having the same number of fabric layers and density as Example B but
incorporating connectors at the strike face in the first fifteen layers
of fabric restored the V50 performance by six percent to an acceptable
value.

Example 3

[0108] In this example, thirteen layers of fabric F2 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through, and orthogonal to, the thirteen layers. The connector material
was 453 dtex (408 denier) cotton thread from United Thread Mills having a
force to break of 18.5 N. The connector pitch length was 6.4 mm and the
connector row spacing was 12.8 mm. The connector lines enclosed a
connector area of 161 sq. mm. The sub-assembly with the connectors was
then combined with thirteen loose layers of fabric F2 of about 38
cm×38 cm (15''×15'') by corner stitching into an article with
an areal density of 4.88 kg/m2. The corner stitching thread was 800
dtex (720 denier) Kevlar® under the tradename B-92 from Imperial
Threads Inc. Ballistic tests were conducted using 17 grain FSPs against
targets supported on an aluminum 24 ga, 0.20, 2024-T3 frame and clamp
backing plate. The test articles were arranged such that the layers
having the connectors were facing the projectile. Results of the
ballistic tests of four targets gave V50 values between 552 and 575 m/s
with an average value of 569 m/s.

[0109] Comparison of results for examples E, F and 3 show that reducing
the areal density by seven percent brought about a four percent knockdown
in V50 value. Incorporating connectors at the strike face in the first
thirteen layers of fabric recovered all but one percent of V50
performance. Example L demonstrated that sewing connectors throughout all
the fabric layers resulted in a very low V50 value. The use of connector
material having a force to break above 65 N also gave a low V50 as
exemplified by Example J.

Example 4

[0110] In this example, fifteen layers of fabric F1 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through, and orthogonal to, the fifteen layers. The connector material
was 453 dtex (408 denier) cotton thread from United Thread Mills having a
force to break of 18.5 N. The connector pitch length was 6.4 mm and the
connector row spacing was 12.8 mm. The connector lines enclosed a
connector area of 161 sq. mm. The sub-assembly with the connectors was
then combined with sixteen loose layers of fabric F1 of about 38
cm×38 cm (15''×15'') by corner stitching into an article with
an areal density of 4.68 kg/m2. The corner stitching thread was 800
dtex (720 denier) Kevlar® under the tradename B-92 from Imperial
Threads Inc. Ballistic tests were conducted using 17 grain FSP's against
targets supported on an aluminum 24 ga, 0.20, 2024-T3 frame and clamp
backing plate. The test articles were arranged such that the layers
having the connectors were facing the projectile. Results of the
ballistic tests of four targets gave V50 values between 564 and 605 m/s
with an average value of 585 m/s.

[0111] Comparison of results for examples G,H and 4 show that Example G
having an article weight of 5.28 kg/m2 had an acceptable V50 whereas
Example H at a reduced areal density of 4.68 kg/m2 had a V50 value
five percent lower and below the desired target value. Example 4, having
the same number of fabric layers and density as Example H but
incorporating inventive connectors at the strike face in the first
fifteen layers of fabric resulted in an almost a full recovery of V50
performance.

Example 5

[0112] In this example, fifteen layers of fabric F1 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through, and orthogonal to, the fifteen layers. The connector material
was 453 dtex (408 denier) cotton thread from United Thread Mills having a
force to break of 18.5 N. The connector pitch length was 6.4 mm and the
connector row spacing was 19.1 mm. The connector lines enclosed a
connector area of 363 sq. mm. The sub-assembly with the connectors was
then combined with sixteen loose layers of fabric F1 of about 38
cm×38 cm (15''×15'') by corner stitching into an article with
an areal density of 4.68 kg/m2. The corner stitching thread was 800
dtex (720 denier) Kevlar® under the tradename B-92 from Imperial
Threads Inc. Ballistic tests were conducted using 17 grain fragment
simulating projectiles (FSP's) against targets supported on an aluminum
24 ga, 0.20, 2024-T3 frame and clamp backing plate. The test articles
were arranged in the tests such that the layers having the connectors
were facing the projectile. Results of the ballistic tests of two targets
gave V50 values of 558 and 570 m/s with an average value of 564 m/s.

Example 6

[0113] In this example, fifteen layers of fabric F1 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through, and orthogonal to, the fifteen layers. The connector material
was 453 dtex (408 denier) cotton thread from United Thread Mills having a
force to break of 18.5 N. The connector pitch length was 6.4 mm and the
connector row spacing was 25.4 mm. The connector lines enclosed a
connector area of 645 sq. mm. The sub-assembly with the connectors was
then combined with sixteen loose layers of fabric F1 of about 38
cm×38 cm (15''×15'') by corner stitching into an article with
an areal density of 4.68 kg/m2. The corner stitching thread was 800
dtex (720 denier) Kevlar® under the tradename B-92 from Imperial
Threads Inc. Ballistic tests were conducted using 17 grain fragment
simulating projectiles (FSP's) against targets supported on an aluminum
24 ga, 0.20, 2024-T3 frame and clamp backing plate. The test articles
were arranged in the tests such that the layers having the connectors
were facing the projectile. Results of the ballistic tests of three
targets gave V50 values of 562 and 589 m/s with an average value of 574
m/s.

Example 7

[0114] In this example, fifteen layers of fabric F1 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through, and orthogonal to, the fifteen layers. The connector material
was 453 dtex (408 denier) cotton thread from United Thread Mills having a
force to break of 18.5 N. The connector pitch length was 6.4 mm and the
connector row spacing was 6.4 mm. The connector lines enclosed a
connector area of 40 sq. mm. The sub-assembly with the connectors was
then combined with sixteen loose layers of fabric F1 of about 38
cm×38 cm (15''×15'') by corner stitching into an article with
an areal density of 4.68 kg/m2. The corner stitching thread was 800
dtex (720 denier) Kevlar0 under the tradename B-92 from Imperial Threads
Inc. Ballistic tests were conducted using 17 grain fragment simulating
projectiles (FSP's) against targets supported on an aluminum 24 ga, 0.20,
2024-T3 frame and clamp backing plate. The test articles were arranged in
the tests such that the layers having the connectors were facing the
projectile. Results of the ballistic tests of two targets gave V50 values
of 571 and 576 m/s with an average value of 574 m/s.

[0115] A comparison of the results from Examples 4 to 7 show that the V50
ballistic performance of a fabric assembly in which the connectors
enclose an area of about 161 sq. mm. is very good and that enclosed areas
of about 363 sq. mm. and about 40 sq. mm. represent the upper and lower
limits respectively of enclosed areas that give acceptable ballistic
performance.

Example 8

[0116] In this example, fifteen layers of fabric F1 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through and orthogonal to the fifteen layers. The connector material was
2400 dtex (2160 denier) cotton thread G4-Tx240 from Saunders Thread
Company having a force to break of 40.1 N. The connector pitch length was
6.4 mm and the connector row spacing was 12.8 mm. The connector lines
enclosed a connector area of 161 sq. mm. The sub-assembly with the
connectors was then combined with sixteen loose layers of fabric F1 of
about 38 cm×38 cm (15''×15'') by corner stitching into an
article with an areal density of 4.68 kg/m2. The corner stitching
thread was 800 dtex (720 denier) Kevlar® under the tradename B-92
from Imperial Threads Inc. Ballistic tests were conducted using 17 grain
FSP's against targets supported on an aluminum 24 ga, 0.20, 2024-T3 frame
and clamp backing plate. The test articles were arranged such that the
layers having the connectors were facing the projectile. Results of the
ballistic tests of four targets gave V50 values between 562 and 576 m/s
with an average value of 571 m/s.

Example 9

[0117] In this example, fifteen layers of fabric F1 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through and orthogonal to the fifteen layers. The connector material was
453 dtex (408 denier) cotton thread from United Mills having a force to
break of 18.5 N. The connector pitch length was 6.4 mm and the connector
row spacing was 12.8 mm. The connector lines enclosed a connector area of
161 sq. mm. The sub-assembly with the connectors was then combined with
sixteen loose layers of fabric F1 of about 38 cm×38 cm
(15''×15'') by corner stitching into an article with an areal
density of 4.68 kg/m2. The corner stitching thread was 800 dtex (720
denier) Kevlar® under the tradename B-92 from Imperial Threads Inc.
Ballistic tests were conducted using 17 grain FSP's against targets
supported on an aluminum 24 ga, 0.20, 2024-T3 frame and clamp backing
plate. The test articles were arranged such that the layers having no
connectors were facing the projectile i.e. the layers having the
connectors were at the body side. Results of the ballistic tests of four
targets gave V50 values between 576 and 590 m/s with an average value of
583 m/s.

[0118] This Example shows that an assembly in which the connected fabric
layers face away from the strike direction will give an increased V50
when compared to an assembly with no connected layers, provided the
connecting material has a force to break of below 65 N and the connectors
enclose an area of between 50 to 350 sq. mm.

Example 10

[0119] In this example, fifteen layers of fabric F1 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through and orthogonal to the fifteen layers. The connector material was
351 dtex (316 denier) Kevlar® thread from United Thread Mills having
a force to break of 29 N. The connector pitch length was 6.4 mm and the
connector row spacing was 12.8 mm. The connector lines enclosed a
connector area of 161 sq. mm. The sub-assembly with the connectors was
then combined with sixteen loose layers of fabric F1 of about 38
cm×38 cm (15''×15'') by corner stitching into an article with
an areal density of 4.68 kg/m2. The corner stitching thread was 800
dtex (720 denier) Kevlar® under the tradename B-92 from Imperial
Threads Inc. Ballistic tests were conducted using 17 grain FSP's against
targets supported on an aluminum 24 ga, 0.20, 2024-T3 frame and clamp
backing plate. The test articles were arranged such that the layers
having the connectors were facing the projectile. Results of the
ballistic tests of four targets gave V50 values between 583 and 594 m/s
with an average value of 588 m/s.

[0120] Comparison of the results from Examples J, K and 10 shows that the
use of a connector material having a low force to break (29N) gives a
significantly better V50 compared to use of a connector having a high
force to break (69.8N).

Example 11

[0121] In this example, fifteen layers of fabric F1 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through the fifteen layers. The connector material was 453 dtex (408
denier) cotton thread from United Mills having a force to break of 18.5
N. The connector pitch length was 6.4 mm and the connector row spacing
was 12.8 mm. The connector lines enclosed a connector area of 161 sq. mm.
The sub-assembly with the connectors was then combined with sixteen loose
layers of fabric F1 of about 38 cm×38 cm (15''×15'') by
corner stitching into an article with an areal density of 4.68
kg/m2. The corner stitching thread was 800 dtex (720 denier)
Kevlar® under the tradename B-92 from Imperial Threads Inc. Ballistic
tests were conducted using 9 mm 124 grain FMJ bullets against targets
supported on a Roma Plastina number 1 clay backing medium. The test
articles were arranged such that the layers having no connectors were
facing the projectile i.e. the layers having the connectors were at the
body side. Results of the ballistic tests of four targets gave V50 values
between 465 and 480 m/s with an average value of 473 m/s.

[0122] Like Example 9, this example shows that an assembly in which the
connected fabric layers face away from the strike direction will give an
increased V50 when compared to an assembly with no connected layers,
provided the connecting material has a force to break of below 65 N and
the connectors enclose an area of between 50 to 350 sq. mm.

Example 12

[0123] In this example, fifteen layers of fabric F1 of about 38
cm×38 cm (15''×15'') were held together by connectors sewn
through the fifteen layers. The connector material was 351 dtex (316
denier) Kevlar® thread from United Thread Mills having a force to
break of 29 N. The connector pitch length was 6.4 mm and the connector
row spacing was 12.8 mm. The connector lines enclosed a connector area of
161 sq. mm. The sub-assembly with the connectors was then combined with
sixteen loose layers of fabric F1 of about 38 cm×38 cm
(15''×15'') by corner stitching into an article with an areal
density of 4.68 kg/m2. The corner stitching thread was 800 dtex (720
denier) Kevlar® under the tradename B-92 from Imperial Threads Inc.
Ballistic tests were conducted using 9 mm 124 grain FMJ bullets against
targets supported on a Roma Plastina number 1 clay backing medium. The
test articles were arranged such that the layers having no connectors
were facing the projectile i.e. the layers having the connectors were at
the body side. Results of the ballistic tests of four targets gave V50
values between 492 and 505 m/s with an average value of 498 m/s.

Example 13

[0124] In this example, twenty layers of fabric F3 of about 38 cm×38
cm (15''×15'') were assembled with a perforated film layer IL1
between each fabric layer to form a first section. The layers of fabric
and film were held together by connectors sewn through the twenty layers.
The connector material was 351 dtex (316 denier) Kevlar® thread from
United Thread Mills having a force to break intention of 29 N. The
connector pitch length was 6.4 mm and the connector row spacing was 12.8
mm. The connector lines enclosed a connector area of 161 sq. mm. A
further forty layers of fabric F3 of about 38 cm×38 cm
(15''×15'') were assembled with a perforated film layer IL1 between
each fabric layer to form a second section. No connector material was
applied to the second section. Sections 1 and 2 were combined with one
non-perforated film layer IL1 between the two sections. The assembly of
film and fabric had an areal density before consolidation of 9.89
kg/m2. The assembly was then consolidated to form a hard plate at a
pressure of 0.42 bar, a temperature of 178° C. with a hot press
time of 15 minutes followed by a dwell time of 30 minutes. The resin
content of the fabric-film assembly after consolidation was about 6.2
percent. The areal density of the plate after consolidation was 9.82
kg/m2 Ballistic tests were conducted using 16 grain RCC steel
projectiles. The first section was facing the projectile. Results of the
ballistic tests gave a V50 value of 920 m/s.

Example 14

[0125] Example 14 was as Example 13 except that the areal density of the
fabric-film assembly before consolidation of 9.90 kg/m2. The areal
density of the fabric-film assembly after consolidation was 9.82
kg/m2. Ballistic tests were conducted using 16 grain RCC
projectiles. Results of the ballistic tests gave a V50 value of 932 m/s.

[0126] The table below provides a summary of the test results of the
examples pertaining to soft body armor. The results for hard armor show a
V50 improvement of around 6% for a fabric assembly in which one third of
the fabric layers are connected as described in this invention.